What is Test mode (sandbox)?
Test mode runs the full x402 flow — challenge, pay, verify, allow — without spending real USDC. Sandbox keys simulate payments so you can build and CI-test an integration, then flip one environment variable to go live.
Because the wire format is identical between test and live, going live is a configuration change, not a rewrite. This is how you prove an integration end-to-end before a real cent moves.
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